The brain excels in making something from nothing ('jumbled messes'), barred there's enough practice involved.
A good example are cochlear implant (CI) recipients; a CI (Fig. 1) bypasses the degenerate hair cells in the inner ear (cochlea) and stimulates the auditory nerve directly electrically. It receives its input from a speech processor typically worn behind the ear that translates acoustic signals into electrical pulse trains. A wireless radio link takes care of data and energy transfer to the internal parts.
All good, yet CIs feature only about 14-24 electrodes, whereas healthy inner ears contain about 3,500 inner hair cells. The electric currents of those electrodes tend to overlap to the extent that just about 7 channels remain. Hence, the frequency resolution is downgraded to such an extent that CI recipients basically are left with temporal information only, encoded in pulse train variations. As a result, they have to go through an arduous rehabilitation program to learn to recognize speech again, which requires intensive guidance by rehab specialists and a sturdy safety net from partner and family and friends who are willing to support and help in speech recognition training.
Nonetheless, despite their severely degraded hearing capabilities, CI recipients are able to understand speech very well in quiet environments. Oftentimes they are even able to use the phone, i.e., understand speech without the aid of lip reading (!), which is remarkable. The steep learning curves involved are the result of neural plasticity in the brain.
Moreover[,] the child doesn't know what normal vision is like, so probably [they cannot deploy] "guided learning"
Of course they can, just like a child develops to produce speech, it will parrot their parents in doing so. Arnon already brought up sensory substitution, a great example; blind folks for instance can learn to navigate using the BrainPort (Fig. 2) that converts camera images into tactile representations on the tongue (Stronks et al., 2016). Another successful vision aid for the blind is the vOICe, where visual images are transferred to 2D 'soundscapes'. People can learn to make sense of it, mainly by using it and learning to interpret what they hear and relate that to their surroundings. For blind people that will require training; for the BrainPort rehab programs exists, at least in Pittsburgh what I am aware. vOICe is open source and people can download the app on their phones and its highly popular.
One of the prerequisites is that implantation occurs without the patient being deaf for too long. Congenitally deaf born kids are normally implanted within months, to allow full speech recognition and hence speech production to develop. If a person remains sensory deprived for too long, the brain is grossly restructured, and re-developing the lost sense becomes progressively more difficult, in adults and kids alike.
- Lee et al. Front Hum Neurosci (2014); 8: 291
- Stronks et al., Exp Rev Med Dev (2016); 13(10): 919-31
Fig. 1. CI. source: Mayo Clinic
Fig. 2 BrainPort Vision Device (Lee et al. (2014)